1. Field of the Invention
The invention relates in general to an electro-acoustic sensing device, and more particularly to a capacitive electro-acoustic sensing device.
2. Description of the Related Art
In recent years, consumer electronic products have won great popularity on the market, and various electronic products are widely used in modern people's everyday life. As electronic products are directed towards multi-function and small size, manufacturers are engaged in providing products with better integration and lower costs. Many consumer electronic products, such as mobile phones, personal digital assistants (PDAs), digital voice recorders and portable digital music players, adopt micro-electro-mechanical system (MEMS) microphone and speaker for providing better quality of reception and amplification.
One of the commonly used structures of micro-electro-mechanical system microphone is a system in package (SIP) structure, in which multiple chips are installed. Please refer to FIG. 1, a cross-sectional view of a conventional micro-electro-mechanical system microphone is shown. In a micro-electro-mechanical system microphone 100, independent elements such as the acoustic wave sensing chip 110, the circuit chip 130 and the surface mount component 150 are respectively disposed on the substrate 170. The protection cover 190 is disposed on the substrate 170 and covers the elements such as acoustic wave sensing chip 110, the circuit chip 130 and the surface mount element 150. The protection cover 190 has a sound entering hole 190a via which the sound signal enters the protection cover 190 and contacts the acoustic wave sensing chip 110. In the micro-electro-mechanical system microphone 100, the acoustic wave sensing chip 110, the circuit chip 130 and the surface mount component 150 are installed on the substrate 170 by way of wire-bonding. The structure and manufacturing process of the micro-electro-mechanical system microphone 100 are complicated, so the manufacturing cost is hard to bring down.